Process for deposition of diamondlike, electrically conductive and electron-emissive carbon-based films

Abstract

A process for depositing amorphous or nanophase diamondlike carbon (DLC) and a-C:H carbon/hydrogen films with variable and controllable properties on the surface of a substrate is disclosed. The process utilizes a combined hydrocarbon ion beam and plasma-activated hydrocarbon gaseous radical flux produced by an end-Hall ion source to yield a film with good electron-emissivity characteristics or high hardness and good optical transparency, as desired. A second ion source providing a beam of argon ions above or together in nitrogen is optionally directed at the substrate for cleaning prior to deposition and for ion-assisted deposition during deposition or for doping.

What is claimed is: 
     
       1. A process for depositing a carbon containing film, such as, amorphous carbon (a-C), amorphous hydrogenated carbon (a-C:H), or, diamondlike carbon (DLC) film on a substrate using an end-Hall ion source, comprising the steps of: a. providing an end-Hall ion source in a vacuum chamber;   b. providing a substrate to be coated within said chamber; and   c. introducing a carbon containing gas into said end-Hall source and forming a carbon containing plasma;   d. controlling the ion energy of said carbon containing plasma and depositing onto said substrate a carbon containing film having electrically conductive and electron-emissive properties, or, high hardness, low electrical conductivity and optical transparent properties, or, a combination of both, depending on the ion energy utilized.   
     
     
       2. A process as in claim 1 including the step of providing an electron source in the end-Hall source. 
     
     
       3. A process as in claim 2 wherein a hollow cathode electron source is used as the electron source. 
     
     
       4. A process as in claim 2 wherein a plasma bridge electron source is used as the electron source. 
     
     
       5. A process as in claim 1 further including the steps of providing a argon ion source and precleaning said substrate by argon ion bombardment before carbon deposition is carried out. 
     
     
       6. A process as in claim 1 further including the steps of providing an ion source and employing argon ion bombardment during carbon deposition for the purpose of adding energy to the deposited film. 
     
     
       7. A process as in claim 1 further including the step of adding hydrogen gas to the carbon containing plasma during carbon deposition for the purpose of reducing graphitelike bonding of said film. 
     
     
       8. A process as in claim 1 further including the step of adding nitrogen gas during carbon deposition for the purpose of doping said carbon containing film with nitrogen to improve the mechanical and electrical properties of said deposited film. 
     
     
       9. A process as in claim 1 wherein said carbon containing gas is a hydrocarbon. 
     
     
       10. A process as in claim 9 wherein said hydrocarbon is taken from the group consisting of methane, ethane, propane, butane, ethylene, propylene, accetylene and mixtures thereof. 
     
     
       11. A process as in claim 9 wherein said hydrocarbon gas is methane. 
     
     
       12. A process as in claim 1 wherein said substrate is taken from the group consisting of ceramics, semiconductors, glass, metals, polymers, papers. 
     
     
       13. A process as in claim 1 wherein said substrate is a semiconductor taken from the group consisting of silicon, germanium, gallium arsanide. 
     
     
       14. A process as in claim 13 wherein said substrate is silicon. 
     
     
       15. A product made in accordance with the process of claim 1. 
     
     
       16. A coated substrate made in accordance with the process of claim 1. 
     
     
       17. The process according to claim 1, further including the step of maintaining a constant current density throughout the depositing of the carbon containing film on said substrate. 
     
     
       18. The process according to claim 17, wherein the value of said constant current density ranges from about 0.2 to 1 mA/cm 2 . 
     
     
       19. The process according to claim 17, wherein the value of said constant current density is about 0.2 mA/cm 2  or more. 
     
     
       20. The process according to claim 18, wherein the deposition rate of said film ranges from 500 Å/min to 2,000 Å/min. 
     
     
       21. A coated substrate made in accordance with the process of claim 17, having a film thickness of from about 10 Å to about 20 micrometers. 
     
     
       22. A coated substrate made in accordance with the process of claim 19, having a film thickness of from about 10 Å to about 20 micrometers. 
     
     
       23. The coated substrate of claim 21, wherein said carbon containing film has an 8 GPa nano-indentation hardness rating. 
     
     
       24. The coated substrate of claim 21, wherein said carbon containing film has a resistivity of 1.1±0.5 ohm cm. 
     
     
       25. The coated substrate of claim 23, wherein said carbon containing film has a resistivity of 1.1±0.5 ohm cm. 
     
     
       26. The coated substrate of claim 21, wherein said carbon containing film emits electrons at 1 μA at 20 volts/μm. 
     
     
       27. The coated substrate of claim 23, wherein said carbon containing film emits electrons at 1 μA at 20 volts/μm. 
     
     
       28. The coated substrate of claim 24, wherein said carbon containing film emits electrons at 1 Å at 20 volts/μm. 
     
     
       29. The process according to claim 1 wherein the ion energy provided by said end-Hall source is defined by a V anode  value of between about 90 eV to about 150 eV. 
     
     
       30. The process according to claim 1 wherein the ion energy provided by said end-Hall source is defined by a V anode  value of about 90 eV to produce a carbon containing film on said substrate characterized as having softer and electron emissive properties. 
     
     
       31. The process according to claim 17 wherein the ion energy provided by said end-Hall source is defined by a V anode  value of about 90 eV to produce a carbon containing film on said substrate characterized as having softer and electron emissive properties. 
     
     
       32. The process according to claim 1 wherein the ion energy provided by said end-Hall source is defined by a V anode  value of about 150 eV to produce a carbon containing film on said substrate characterized as having hard and non-electron emissive properties. 
     
     
       33. The process according to claim 1 further including the step of combining a second ion source with said first ion source to increase the ion energy of said plasma so as to produce a carbon containing deposited film having hard and non-electron emissive properties. 
     
     
       34. The process according to claim 1, wherein the rate of deposition of said carbon film is at least 146 Å/min.